Air traffic at large airports is generally managed and pilots are apprised of danger by an air traffic controller during operating hours of the control tower. Smaller airports, however, rarely have the traffic to justify the expenses associated with the equipment and salaries of the tower crew. As a result, pilots of smaller aircraft generally must monitor air traffic and weather conditions themselves, compounding their full-time task of navigating and piloting the airplane.
Without the guiding voice of an air traffic controller, pilots in the vicinity of airports not having a control tower manage themselves by relaying messages to each other over a shared communication radio frequency known as a Common Traffic Advisory Frequency (CTAF). Basically, the CTAF serves as a bulletin board where pilots broadcast general declarations to alert each other of their planned course of action. Consequently, each airport has its own CTAF channel, which is assigned and published by the FCC and which pilots find through various airport information sources.
There are drawbacks associated with pilots at non-towered airports coordinating their own traffic flow using the CTAF channel. Broadcasts are rarely to a particular party and important messages can be confusing due to the fact that a pilot must rely on the ability of a transmitting party to communicate an intelligible and accurate message. Moreover, an inattentive pilot may not even broadcast a message concerning his intentions at all, leaving pilots unaware of potentially dangerous circumstances. As a result, there is a constant desire among pilots to develop tools to increase awareness and, hence, air traffic safety.
A number of other systems have been proposed to enhance air traffic safety. These systems include electronic surveillance devices, the primary purpose of which is to alert pilots about the presence, and sometimes location, of aircraft and inclement weather conditions that pose an immediate threat to the pilot and passengers on board.
Systems have also been proposed in which a visual display is used to alert pilots when another aircraft is close in proximity. For example, one pilot advisory system tracks the location and associated trajectories of aircraft in the vicinity of a protected aircraft. When the monitored air traffic data indicates that two aircraft are getting too close to each other, the computer generates a climb or descend recommendation and displays the information on a screen for the pilot. Contrasting colors and descriptive symbols on the display aid in conveying the appropriate message to the pilot.
Other weather advisory systems monitor and compile storm location data. At the request of a subscriber-pilot, a microprocessor processes weather data to correct for an aircraft""s position and heading in order to display, on a screen, storm locations relative to the aircraft. In this way, pilots are alerted to the location and presence of dangerous weather conditions, i.e. lightning storms, so that danger may be avoided.
Unfortunately, like other high cost electronics, few owners of smaller aircraft can afford these more elaborate electronic surveillance systems found in larger commercial aircraft. As a result, smaller aircraft are often at a higher risk.
Certain weather advisory systems, however, have been deployed at non-towered airports to assist pilots. Automatic Weather Observation Systems (AWOS) automatically provide weather information to pilots over a dedicated communication frequency. This frequency, like the CTAF channel, is also assigned and published by the FCC. Typically, the AWOS unit will monitor wind speed, direction and other important meteorological characteristics of the airport. After the weather information is compiled and processed by a computer, it is transmitted to pilots over the AWOS channel in the form of a synthesized audio message. After hearing this message on the dedicated channel, an approaching pilot, for example, may select an appropriate landing runway based upon present weather conditions at the airport.
A major drawback of the AWOS, is the fact that it requires a dedicated channel different than the Common Traffic Advisory Frequency (CTAF) channel. To simultaneously monitor both the AWOS and CTAF channels, a pilot must have two radios. And even if two radios are available, it is impractical to listen to two radios at the same time. If a cockpit is equipped with only one radio, the pilot must manually change the channel depending on which information, AWOS or CTAF, is desired at the time. Furthermore, whether or not a given aircraft has two radios, the pilot must still draw their attention away from the CTAF channel to listen to the weather only broadcast from an AWOS. A pilot, as a result, may miss critical flight information while listening to one channel in lieu of the other. Moreover, the act of changing the radio channel takes a pilot""s attention away from the important task of flying the airplane.
Another, deployed weather advisory system involves broadcasting weather information over the CTAF channel in response to pilot requests. One method of making such a pilot information request is by rapidly clicking a pilot""s radio microphone a predetermined number of times. For example, three quick successions of pressing and releasing the transmit button on the cockpit radio indicates a request for an update of the weather in the immediate area. In response to the microphone clicking, the advisory system monitoring the CTAF channel then broadcasts a message based upon present weather conditions, where the length and content of the message depends on the volume of traffic on the CTAF channel. When the volume of traffic on the CTAF channel is heavy, messages are shortened so as not to interfere with pilot transmissions.
Without the guiding voice of an air traffic controller, pilots in the vicinity of small airports must monitor air traffic and weather conditions themselves compounding the full-time task of navigating and piloting the airplane.
It would be an advancement in the art to provide a low cost advisory system that monitors weather and aircraft location information from a centralized base station which automatically broadcasts relevant advisory messages over a shared communication channel to alert pilots of relevant air traffic information.
According to one aspect, the present invention concerns an apparatus for broadcasting pilot advisories at airports. The system comprises a CPU linked to an aircraft monitoring subsystem and a transmitter for broadcasting messages to pilots. The aircraft monitoring subsystem generates aircraft location information that is transferred to the monitoring CPU. The CPU, in turn, uses the data to track aircraft in the monitored airspace. Based on the this information, the CPU generates advisory messages that are automatically broadcasted to pilots via the transmitter, providing them with air traffic information.
In specific embodiments, the present invention includes a weather substation linked to the monitoring CPU and a data storage device for recording relevant air traffic information. Based on the monitored weather conditions and air traffic trends, the CPU issues advisories to pilots in the monitored airspace. Weather advisories may depend on the location of the aircraft. For example, an aircraft approaching a runway, presumably attempting to land, would be issued an advisory regarding wind speed and direction. In addition, an advisory message describes procedures with respect to landing an aircraft or other related activities. Advisories are generated using a voice synthesizer so that a pilot, beyond the limitations of visually scanning for traffic, may listen to a radio channel to keep abreast of important air traffic information. In other respects, an operator interface enables airport personnel to program messages related to specific airport incidents, conditions and/or procedures.
Preferably, the pilot advisory system includes aircraft surveillance equipment that monitors the location of aircraft in a given airspace. Examples include mode A, C or S receivers and transponders. The monitoring computer, while tracking the aircraft locations, labels each aircraft with a unique name to facilitate targeting sensible advisories to appropriate parties. Further, the invention includes alternate communication links where messages are transmitted to parties other than pilots. For example, using a telephone link, appropriate authorities are notified if an aircraft comes to an abrupt halt, presumably as a result of a an aircraft accident, while attempting to land or takeoff from a runway.
In other aspects of the embodiments, a device is provided that monitors, for example, a communication channel, and detects pilot advisory requests. In response to a pilot request, a transmitter broadcasts the information over the radio channel. In this way, a pilot, for example, retrieves location information to resolve uncertainty as to bearing or position. The radio channel is also monitored for activity so that the length of an advisory message is optimized, since it is undesirable to interfere with pilot conversations.
According to another aspect, the present invention also concerns a method for broadcasting pilot advisories at airports. The method includes monitoring and tracking aircraft location information in an airspace, generating advisories in response to the aircraft location information and broadcasting the advisories to pilots over a radio channel. In this way, pilots are alerted to air traffic information.
Another aspect of the invention is the ability of the airspace monitoring device to determine aircraft location in three dimensional space. This includes interrogating aircraft with surveillance devices, such as mode A, C or S transponders, and converting the received signals into aircraft location information. The monitoring computer, while tracking the aircraft locations, labels each aircraft with a unique name to facilitate targeting advisories to appropriate parties. And in addition to conveying advisory messages to pilots, the advisory system also conveys messages to parties other than pilots using an alternative communication link such as a telephone line.
In other specific embodiments, the claimed invention includes monitoring a radio channel and detecting pilot advisory requests. A monitoring computer, in response, generates an advisory message that is broadcasted over the the radio channel.